The automotive industry has turned to the use of interior trim components such as door panels comprising a polyvinyl chloride shell. See, for example, the trim components disclosed in U.S. Pat. No. 3,123,403. The acceptance of such components has been because inter alia this type of construction permits a wide latitude in styling and color, and grain effects which are most desired, particularly in the interior design of automobiles.
The current state of the art includes a preformed grained vinyl shell made from dry thermoplastic powder particles which are applied to a heated shell mold from a powder box to form a continuous one piece shell.
In order to enhance the interior decor of an automobile, interior door panels and other parts have been prepared which include two separate plastic shell sections joined by a mechanical fastener.
U.S. Pat. No. 4,562,025, issued Dec. 31, 1985, with a common assignee to the present application, covers a Mold Method and Apparatus for Multi-Color Plastic Shells in which shell segments have their edges bonded at a common break-line.
U.S. Pat. No. 4,610,620 issued Sept. 9, 1986 discloses apparatus for loading and releasing a precharge of two or more colors of thermoplastic powder from separate compartments in a charge box means for gravity flow into a mold configured to produce two shell segments and a separate overlapping color connector to bond the shell segments to form a one piece shell with two or more color tones to enhance the decor of the interior of an automobile.
In the '620 patent, an open-ended charge box means is provided with a divider wall to form two or more separate compartments, each filled with a predetermined quantity of different colored powder. The mold has a division surface which cooperates with the divider wall to separate the powder content in each compartment of the charge box means. The charge box releases the powder from the separate charge box compartments to flow evenly across the open end of the mold by gravity. A fixed gasket seals the division surface and the divider wall so as to produce separate two tone segments on the heated surfaces of the mold. In theory, the seal gasket keeps the division surface clean for a subsequent application of material thereagainst to form a connector that bonds the previously cast two tone segments to form a single piece article with an integral joint between two tone segments. In practice, such a fixed gasket must conform to a division surface on each of a number of heated molds. The molds can be heated by suitable means such as hot air units of the type shown in U.S. Pat. No. 4,623,503 dated Nov. 18, 1986. Tolerance differences in the mold dimensions may leave margin gaps between the fixed gasket and the division surface. Powder from the charge box can seep into such gaps onto the division surface to create color smudges in the finish bonded connector.